Dr. Shashidhar Patil presented on amblyopia (lazy eye) at a symposium moderated by Dr. Arvind L. Tenagi. Amblyopia is a common vision problem in children caused by abnormal visual development that results in decreased vision in one or both eyes. It can be prevented or reversed with early intervention before age 8. Treatment involves prescribing corrective lenses, removing any obstructions to vision, and occluding the better eye to force use of the amblyopic eye. Occlusion therapy works best when started early and continued consistently over time with good parental cooperation.

1. SYMPOSIUM
TOPIC---AMBLYOPIA
MODERATOR- DR ARVIND.L.TENAGI
PROFESSOR AND HOD
DEPT OF OPHTHALMOLOGY
KLE-KAHER-JNMC
PRESENTER-DR SHASHIDHAR PATIL

2. Introduction
• Amblyopia, or lazy eye, refers to a unilateral or bilateral
decrease of vision, in one or both eyes, caused by
abnormal vision development in childhood or infancy.
• It is a common vision problem in children and is the
leading cause of decreased vision among children.
• Most vision loss is preventable or reversible with the
right kind of intervention.
• If not treated early results in permanent loss of vision.

3. Definition.
• It refers to a partial loss of sight in one or both
eyes,caused by abnormal visual development
secondary to abnormal visual stimulation in
the absence of ophthalmoscopic or other
marked objective signs.
• It is a spectrum of visual loss, ranging from
missing a few letters on 20/20 lines to hand
motion vision.

4. ..
• For practical purposes, amblyopia is labelled,
when there is at least two snellen lines
differences in the visual acuity between the
eyes.
• Amblyopia occurring in a patient with
strabismus is not a sensory adaptation per se,
but the consequence of suppression which is
sensory adaptation.

5. Epidemology
• Prevalence ranges between 0.5 to 3.5 percent
in school going children.
• Both sex are equally affected.
• No race is immune to it.
• No fixed herediatary factor is seen, however
the predisposing causes like refractive errors ,
squint may have genetic background.

6. …
• An increased risk exists in those children who
are
• developmentally delayed.
• were premature.
• have a positive family history.

7. classification
• There is no unanimity in classification.
• Various classification have been done on the
basis of presumed physiopathology of the
condition.
• Many of the terms used in past are either
avoided or altogether discarded eg –toxic
amblyopia.

8. ..
• Strabismic amblyopia-it is due to abnormal
interaction between two eyes due to squint.
• Anisometropic amblyopia-due to uncorrected
unequal refraction into eye.
• Stimulus deprivation amblyopia(formerly
called as amblyopia exanopsia)-caused due to
blurred retinal image secondary to media
opacities-eg-traumatic or congenital cataract ,
corneal opacity, ptosis.

9. ..
• Ametropic amblyopia is caused due to high
uncorrected refractive error.
• Meridional amblyopia due to high astigmatism
in particular meridian.
• Amblyopia of arrest (obsolete)-due to arrest of
development of vision.
• Amblyopia of extinction(obsolete)-due to
secondary loss of vision.

10. ..
Most widely used classification is to divide
amblyopia into—
• organic amblyopia -irreversible –refers to partial
visual loss caused by undetectable organic lesions in
eye or in the visual pathway.eg- toxic amblyopia.
• Functional amblyopia-refers to obligatory psychical
suppression of the retinal image-it is reversible in
large number of cases and depending on the cause,
may be anisometropic , strabismic , meridonial , or
stimulus deprivation.

11. ..
• For practical purposes the best way is to
classify amblyopia as---
• Amblyopia with squint.
• Amblyopia without squint--also known as
straight eye amblyopia.

12. Pathophysiology.
• Amblyopia develops due to failure of visual
pathway development, which may start at
birth or soon after.
• Development of amblyopia after full
maturation of visual pathway is rare.
• Onset after six to seven years is almost
unknown.

13. …
• For development of visual pathway it is
essential to have a clearly formed image on
the macula.
• The macular development is stretched up to 6-
7 years post-natal.
• Any derangment of formation of vision during
this period is bound to cause amblyopia.
• Amblyopia developing early is more difficult to
manage than those developing later.

14. ..
• Anything that prevents formation of equally
clear image on both the maculae will result in
amblyopia.
• Physical obstruction like ptosis , corneal
opacity , lenticular opacity , anisometropia or
squint will result in amblyopia.
• Three critical periods of human visual acuity
development have been determined.

15. ..
• During these time periods, vision can be affected by
the various mechanisms to cause or reverse
amblyopia.
• The development of visual acuity from the 20/200
range to 20/20, which occurs from birth to age 3-5
years.
• The period of the highest risk of deprivation
amblyopia, from a few months to 7 or 8 years.

16. ..
• In cases of bilateral amblyopia, the basic
pathology is a significant blurred retinal image
in each eye causing a disruption of normal
visual development.
• This disruption must occur during the critical
period of visual development (the first 8-10
years of life).

17. ..
• The period during which recovery from
amblyopia can be obtained, from the time of
deprivation up to the teenage years or even
sometimes the adult years.
• Whether different visual functions (eg, contrast
sensitivity, stereopsis) have different critical
periods is not known. In the future,
determination of these time frames may help
modify treatment of amblyopia.

18. ..
• The depth of damage depends on the severity of the blur, the
length of time of the abnormal vision, and the age of onset of the
insult.
• The pathology involved in unilateral amblyopia can be twofold.
• Retinal image blur in one eye can inhibit cortical activity from one
eye, preventing normal visual development.
• Alternatively, misaligned eyes can prevent the normal process of
fusion from taking place. This can result in suppression of the
deviating eye, diminishing the acuity of the eye and loss of
binocularity.

19. Neural basis.
• Abnormal visual stimulation during the critical
period of visual development results in brain
damage.
• Structural and functional damage occurs in the
lateral geniculate nucleus and the striate cortex -
cortex of the visual center in the occipital lobe in
the form of atrophy of connections, loss of cross-
linking between connections and loss of laterality
of connections.

20. Characteristics of amblyopia.
• Amblyopia starts in the critical period of
development of visual pathway.
• It is seen in children under six to seven years
of age.
• If amblyopia is not treated before eight years
of age it becomes permanent.
• Amblyopia is mostly uni-occular but also
bilateral in very small percentage.

21. ..
• It is not possible for parents to know that child
is amblyopic unless the child undergoes
examination of the vision.this happens more
often in children who have amblyopia in-spite
of straight eyes.
• In contrast to this child may be brought with
squint and found to have amblyopia. This is
known as amblyopia with squint.

22. ..
• Diminished distant vision-the amblyopic eye
always has poorer vision than the normal fellow
eye.
• A difference of 2 lines on snellen’s chart after
best correction is diagnostic.
• Vision in amblyopic eye may be as low as
perception of light in congenital squint.
• Generally, ranges between 6/12-6/18.

23. ..
• A child may have 6/36 vision before starting
treatment and end up with 6/12 vision. This eye will
still be considered to be amblyopic.
• CROWDING PHENOMENON-an amblyopic eye has
better vision when single optotypes are shown but
when letters of same size in line are shown , the child
is unable to read them.
• The greater the difference between the single letter
vision and linear vision , poorer is the prognosis.

24. ..
• Vision with neutral density filter-in non
amblyopic eye if neutral density filter is put in
front of the eye , the vision is reduced by one
or two lines but not in amblyopic eye when
neutral density filter of increasing strength is
put in front of the eye, the vision either
remains same or even improves.

25. ..
• In case of organic amblyopia eg-toxic
amblyopia vision is markedly reduced with
neutral density filter.
• The explanation for this phenomenon-is-the
scotopic and mesopic vision of an amblyopic
eye is equal to non amblyopic eye but less in
photopic vision.
• Placing the neutral density filter simulates
scotopic vision , thus it is not affected.

26. ..
• Colour vision and dark adaptation are normal
in amblyopia.
• Contrast sensitivity ,grating acuity , vernier
acuity and spatial localisation are lowered.
• Visual evoked response to pattern stimuli is
poorer in amblyopic eye.
• Mild degree of RAPD may be present.
• Amblyopic eye may have mobility defect in the
form of pursuits , fixation and saccades.

27. lea grating acuity charts.

28. Vernier acuity.

29. Contrast sensitivity

30. A person with normal visual acuity but poor contrast sensitivity
might see the trees in the foreground clearly (high contrast), but
have trouble seeing the contours of the mountains against the sky in
the background (low contrast).

31. Spatial localisation

32. ..
• There may be latent nystagmus.
• There may be poor accomodation.
• Severe degree of amblyopia may have
eccentric fixation.

33. ..
• Toxic amblyopia , nutritional amblyopia , and
amblyopia in various neuropathies like
retrobulbar neuritis do not fit into the
definition of amblyopia.

34. Toxic amblyopia
• Also known as toxic/nutritional optic
neuropathy.-include those conditions wherein
visual loss results from damage to the optic nerve
fibers due to the effects of exogenous or
endogenous poisons.
• This entity includes conditions like-
-Tobacco amblyopia.
-Ethyl-alcohol amblyopia.
-Methyl alcohol amblyopia.
-Quinine amblyopia.
-Ethambutol amblyopia.

35. Amblyopia with squint
• Child constantly uses one eye for fixation.
• Deviating eye becomes amblyopic.
• The patients with alternating fixation do not develop
amblyopia.
• Esotropes develop more amblyopia than exotropes .
• Congenital esotropes do not develop amblyopia due to
cross fixation.

36. ..
• Hypertropes generally do not develop
amblyopia as they manage to maintain fusion
by abnormal head posture.
• Micro strabismus causes more amblyopia
when compared to large degree squint.
• Strabismus causes more amblyopia than
anisometropia.
• Strabismic amblyopia is caused due to
suppression of image in the squinting eye.

37. ..
• Amblyopia with squint report for check-up
earlier than straight eye amblyopia , not
because they are aware of diminished vision
but for cosmetic blemish of squint.
• Degree of amblyopia is influenced by duration
of squint rather than age of onset.
• The suppression is at the level of cortex.

38. .
• Earlier the squint develops , deeper is the
amblyopia and more difficult to treat.
• In case of congenital squint where inhibition is
present at birth , the vision in the amblyopic
eye will not improve beyond perception of
light.
• The condition is less amenable to treatment
than straight eye amblyopia.
• No correlation exists between severity of
amblyopia and angle of squint. Microtropias
are known to cause severe amblyopia.

39. STRAIGHT EYE AMBLYOPIA.
• Refractive error is the cause.
• The condition goes unnoticed because the
child is unaware of less vision in one eye and
the parents do not notice because there are
no external signs.
• The eyes have fairly good binocular function.
• The stereopsis is good.
• Chances of eccentric fixation is minimal or
absent.

40. ..
• The blurred image acts as hinderance to
binocular vision.
• Only rough correlation exists between degree
of anisometropia and depth of amblyopia.
• It is possible to have amblyopia in both eyes.
• The condition has better chance of
development following treatment.

41. PHOTOSCREENING
• Photoscreening is a form of vision screening
for children.
• It uses a camera to take images of a child’s
undilated eyes.
• By looking at the configuration of the
crescents of light returning after a flash (red
reflex). The devices can estimate refractive
error and determine which children are at risk
of amblyopia (lazy eye).

42. ..
• These images can be analyzed by a human
interpreter, or by software incorporated into
the equipment to evaluate the alignment of
the eye and estimate refractive error.
• If significant refractive error or a misalignment
appears to be present it can indicate
amblyopia risk factors.

43. ..
• If amblyopia risk factors are felt to be present a referral should
be made for the child to be seen by a pediatric
ophthalmologist for a cycloplegic examination.
• Photoscreening has advantages to more traditional eye chart
acuity screening, and is particularly useful on younger (age 3-
5), preverbal children (under age 3) and non-verbal children.
• Photoscreening usually takes less than a minute to obtain the
necessary images on a child. The only cooperation required is
for the child to briefly look at the camera.

44. ISCREEN

45. plusOPTIX

46. MTI IMAGE

47. Photoscreen image with normal red and corneal light
reflection interpreted as a negative screen.

48. Photoscreen image depicting anisometropia. Notice
the asymmetry between the red reflexes of each eye.

49. Photoscreen image depicting a media opacity. Notice the
central lenticular opacity in the left eye.

50. Photoscreen image depicting exotropia. Notice that the white fixation
dot is peripherally located in the left eye, compared to the normal,
centrally located white fixation dot in the right eye

51. Spot autorefraction device.

52. Treatment
• Management of amblyopia is rewarding
--- If diagnosed early.
--- If treatment is initiated early.
--- If treatment is continued for sufficient time and
maintained for sufficient time after vision has
improved and come to equal levels in both eyes.
• All above factors depends upon compliance of
the patient and cooperation of parents and
teachers.

53. ..
• Management begins with refraction under
cycloplegia followed by prescription of best
possible power in both eyes which gives the
child a comfortable vision according to
standard protocol of presciption of glasses for
children with special attention to astigmatism.

54. ..
• Any opacity in media should be removed , so
should be any physical obstruction like ptosis ,
tumour of lids.
• This is followed by OCCLUSION of sound eye
to begin with.
• Occlusion therapy is a time honoured method
of treatment .

55. ..
• Occlusion therapy should take into
consideration the following parameters---
• -when to start.
• -gap between two visits.
• -type of occulder to be used.
• -how long should occlusion be continued.
• -should the better eye be occluded and how
long.

56. …
• Occlusion should be started as soon as
amblyopia has been confirmed.
• Occlusion after six years of age do not have
much impact , though it has been observed to
give fairly good results up to age of fifteen.
• Occlusion should be complete and constant to
begin with.

57. Occluders.
• Various types of occluders are available.
• Best is a SKIN PATCH attached to forehead and
cheek by an adhesive tape.
• This occludes the eye fully.
• Child has no chance of peep over the patch
which is always possible with spectacle
occluder—DOYNE’S OCCLUDER or ground
glass occluder.
• In cooperative child opaque contact lens may
give equal good results.

58. ..

59. complications
• Occlusion amblyopia in better eye.
• Development of new strabismus.
• Worsening of preexisting strabismus.
• Intractable diplopia.
• Allergic reaction to occluder.
• Infection may develop in occluded eye.

60. penalisation
• Also know as pharmacological defocusing.
• It is considered as a modified type of occlusion
without actually covering the eye.
• This uses cycloplegic drug and spectacle in
various combination to change the
accomodation.
• Vision is blurred in better eye and forcing the
amblyopic eye to see.

61. ..
• The best results are obtained in amblyopia of
moderate depth in moderate hypermetropia.
• Amblyopic eye is given full correction.
• One drop of 1% atropine is instilled in better
eye once a day.
• Follow up and duration similar to that of
occlusion.
• Recommended if child does not tolerate
occlusion or peeks over occlusion.

62. Other treatments
• PLEOPTICS
• CAM VISION STIMULATOR
• SURGERY FOR SQUINT AFTER AMBLYOPIA IS TREATED
• Cataract are operated before starting occlusion.
• Haemagioma of eyelid if present is excised.
• if ptosis present it is also managed surgically.
• MEDICAL TREATMENT-LEVODOPA has been tried in
small groups with some improvement.

63. pleoptics
• Comberg designed an instrument to stimulate
the macula in eccentric fixators.
• The pleoptics is derived from the greek word
pleos meaning full and optikos meaning
pertaing to light.
• The eccentrically fixating retinal areas are
dazzled with bright light while protecting
fovea with the disc projected onto the fundus
and an intermittent stimulation of the macula
with flashes of light.

64. ..
• The treatment is continued untill the fixation
becomes central.
• The only indication is a co-operative and
intelligent child older then 6 yrs or more
having eccentric fixation.
• It is contraindicated in patients above 8 yrs
because of the risk of inducing intractable
diplopia due to stimulation of central fovea in
the presence of eccentric fixation.

65. CAM STIMULATOR.
• Cambell and coworkers proposed a new
treatment for amblyopia.
• Discs are made with light and dark bars of
various widths and rotated at the rate of one
rotation per minute to provide different
orientation to stimulate a variety of brain
cells.
• Seven discs of various spatial frequencies are
used.

66. ..
• Patient views them for seven minutes.
• This is based on the priniciple that visual areas
of brain respond to stimuli of grating of a
specific size at a certain orientation.
• This modality is not used these days.

67. …

68. levodopa
• Levodopa is a precursor of dopamine , a
neurotransmitter known to influence the visual
system at both retinal and cortical levels.
• Animal amblyopic models have been shown to be
deficient in dopamine.
• Carbi-dopa is a peripheral decarboxylase inhibitor
that prevents the breakdown of levodopa at
peripheral sites and allows more of it to cross blood-
retinal barrier.
• Levodopa has been shown to improve visual acuity
in children as well as in adults.

69. Site and mechanism of action.
• Exact site not known.
• Primary site could be retina or the cortex.
• It can act directly at the retina or indirectly at
the cortex through a neurotransmitter.
• Visual deprivation decreases retinal dopamine
concentration.

70. ..
• It influences recepive field properties of
retinal neurons,gap junctions between
horizontal cells.
• It influences Light adaptive movements
between rods and cones and appears to be
involved in visual information processing to
the brain via D-2 receptors.
• In humans high dopamine concentration have
been detected in amacrine and interplexiform
cells.

71. ..
• The physiological role of dopamine in visual
function in man is indicated by alteration of
VEP in parkinson’s disease,which is
characterised by dopamine deficiency.
• Levodopa intake increases ERG b-
wave,selectively changes amplitude of
oscillatory potentials and reduces the implicit
time of pattern VEP and pattern ERG.

72. ..
• Plasticity of visual system during this sensitive
of visual development is dependent on inputs
from non-adrenergic neurons and is subject to
pharmacological manipulations.
• Levodopa either extends or reactivates the
visual system’s sensitive period of neural
plasticity.

73. SIDE EFFECTS
• NAUSEA.
• VOMITING.
• DIARRHEA.
• HEART BURN.
• ABDOMINAL PAIN.
• SLEEPINESS.
• MOOD CHANGES.
• DECREASED RESPIRATION AND HEART RATE.
• NOCTURNAL INCONTINENCE.
• TIREDNESS.
• DIZINESS.
• HALLUCINATIONS.

74. CITICOLINE.
• THIS DRUG administration in adult volunteers
demonstrated improvement lasting over six
months in visual acuity of both amblyopic and
dominant eyes.
• Even contrast sensitivity and VEP were
significantly improved.

75. REFERENCES
• BCSC SERIES –AMERICAN ACADEMY OF
OPHTHALMOLOGY.
• AIOS CME SERIES NO -18
• PAEDIATRIC OPHTHALMOLOGY BY P.K.MUKHERJEE.
• PAEDIATRIC OPHTHALMOLOGY –CLINICAL GUIDE-BY
P.F.GALLIN.
• VON NOORDEEN-STRABISMUS.
• ZIA CHOWDHARI-PG OPHTHALMOLOGY
• MSO SERIES-A.K.KHURANA.
• UG TEXTBOOK-A.K.KHURANA.
• INTERNET-EYEROUNDS AND EYEWIKI WEBSITES
• MEDSCAPE WEBSITE ARTICLE.

76. THANK YOU